| POLYMERS Vol.64 No.10 |
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COVER STORY
Self-Organization: From Phenomenology to Technology |
| COVER STORY: Highlight Reviews |
| Breaking the Symmetry – Assembly and Applications of Anisotropic and Janus Structures | Bat-El PINCHASIK, Helmuth MÖHWALD, and Andre SKIRTACH |
| <Abstract> In this mini-review, assembly of anisotropic and Janus particles are described together with their diversified applications. Various classes of anisotropic and Janus particles are considered: liposomes and vesicles, polymeric capsules and particles, whose modification can be divided into: a) self-assembly, b) self-organization, wherein self-assembly is accompanied by means of externally applied fields, and c) modification by means of externally applied sources. Self-propulsion and self-motion are some of the most notable examples of the use of such structures, whereas a number of applications in biomedicine, surface cleaning, switches are also described. |
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| Recent Topics in Pattern Formation Theory | Yasumasa NISHIURA |
| <Abstract> Two recent topics arising in pattern dynamics are presented. One is a characterization of amorphous structures by using computational topology, especially persistent diagrams that extract the information of size and shape of various holes embedded in amorphous structures. The other is about an organizing center for the pulse generators arising in reaction diffusion systems with heterogeneities. Although the kinetics is of the excitable type, pulses can be produced spontaneously without external force from the existing heterogeneities in the media. It turns out that a double homoclinic loop to an unstable pattern created by the heterogeneity is responsible for the generating mechanism through the intensive search of all relevant solutions. These two examples show that huge reduction of information is possible via two mathematical methodologies. Keywords: Pattern Formation / Bifurcation / Dynamical System Theory / Applied Analysis |
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| Inorganic-Organic Hybrids by Surface Modification Based on Self-Assembled Monolayers | Naokazu IDOTA, Yoshiyuki SUGAHARA |
| <Abstract> Design of interfaces is an important factor in control of the structures and properties of inorganic-organic hybrid materials, and surface modification with self-assembly monolayers (SAM) can provide interesting inorganic-organic hybrid materials. Here, we focus on SAM-based surface modification of layered inorganic materials via grafting reactions. Layered perovskites can be modified with alcohols using alcohol-exchange reactions to yield alkoxy-modified products. Methods of surface modification with organophosphonic acids have also been developed for modification of layered perovskites and layered potassium hexaniobate. Modification with organophosphonic acids is more attractive than modification with common silylation reagents, since homocomdensation is unlikely to occur under moderate conditions. Exfoliation of SAM-modified materials provides nanosheets covered with SAM. Since these SAM-modified nanosheets exhibit excellent compatibility with polymers as well as interesting surface properties, they can be employed for preparation of polymer-based hybrid materials. A similar strategy can be employed for surface modification of titanium oxide nanoparticles. Keywords: Inorganic-Organic Hybrid Materials / Surface Modification / Alcolol-Exchange Reaction / Organophosphonic Acid / Layered Materials / Nanoparticles |
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| COVER STORY: Topics and Products |
| Self-Assembly of Blockcopolymer | Mikihito TAKENAKA |
| <Abstract> Blockcopolymers form long-range ordered periodical structure in the order of 10 nm to 100 nm in their ordered state. Non-equiribrium structure Ordered Bicontinuous Double Diamond (OBDD) was obtained in triblocktercopolymer with solvent cast process, where two step phase separation including dissordered state to cylinder structure, and cylinder structure to OBDD. Two step phase separation processes during solvent cast processes in triblocktercopolymer provide a new way to control of their morphologies. Directed self-assembly (DSA) combines top-down conventional lithographic technology with bottom-up self-assembly. DSA can correct point defects in the resist pattern formed by top-down method and attain the density multiplication of the template patterns. DSA can be applicable in semiconductor logic systems. Keywords: Blockcopolymer / Directed Self-Assembly / Solvent Cast Process / Chemical Registration / Bottom-up Process / Top-down Process / Density Multiplication |
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| Nanostructures Formed in Polymer Particles by Self-Organization | Hiroshi YABU |
| <Abstract> Phase separation in polymer blends and block copolymers in confined spaces has received great interest since novel types of phase separation structures, which are different from those in bulk state, are formed. Polymer blend and block copolymer particles were prepared by originally developed “Self ORganized Precipitation (SORP)” method, and their phase separation structures were observed by transmission electron microscopy. Janus, core-shell, lamellae and other unique phase separation structures were formed by changing the combination of polymers, size of particles, and other parameters. Functionalization of nanostructured polymer particles with inorganic and metal nanoparticles were also performed. When negatively charged gold nanoparticles were attached to positively charged amino-terminated polybutadiene and polystyrene core-shell particles, gold nanoparticles formed densely packed arrays on their shells, and show strong enhancement of surface enhanced Raman scattering signals. These functionalized and nanostructured composite particles allow accessing a novel class of nanomaterials. Keywords: Self-Organization / Phase Separation / Block Copolymers / Polymer Blends / Polymer Particles / Confinement |
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| Patterned Model Membrane Based on a Polymerized Lipid Bilayer | Kenichi MORIGAKI |
| <Abstract> Association of membrane-bound molecules to lipid micro-domains (lipid rafts) is believed to play critical roles in the biological membrane, but its roles remain elusive due to their complex and dynamic nature. We developed a micropatterned model biological membrane that could control the distribution of membrane-bound lipid and protein molecules with pre-defined geometries. The model system was composed of polymeric and fluid phospholipid bilayers supported on a glass substrate. By lithographically modulating the densities of polymeric bilayer domains, liquid-ordered (Lo) and liquid-disordered (Ld) bilayer phases in the fluid bilayer preferentially accumulated in the polymer-free region and partially polymerized region, respectively. We observed that membrane-bound proteins were sorted between the membrane regions according to their affinities to lipid phases. We evaluated the affinities of membrane-bound molecules to lipid rafts by measuring their distributions in the micropatterned membrane. Quantitative evaluation of the interactions between membrane proteins and lipid rafts should help to elucidate the functional roles of micro-domains in the biological membranes. Keywords: Biological Membrane / Lipid Bilayer / Polymerized Bilayer / Photo-Lithography / Supported Membrane / Membrane Protein / Rhodopsin / Lipid Raft |
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| Polymer Science and I: A Personal Account |
| In Pursuit of My Original Materials | Shinichi MOCHIZUKI |
| <Abstract> Most researchers in the field of biomaterials have developed their original materials and applied them for uses in medicine, industry and environment. It is important for me to develop my original materials. I always get new ideas through collaboration with medical doctors and researchers in companies. |
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| Front-Line Polymer Science |
| Surface Engineering for Cell-Mediated Therapy | Yasuhiko IWASAKI |
| <Abstract> The cell surface can be considered as among the most sophisticated materials generated in nature because of its biocompatibility and molecular recognition. The cell surface engineering with synthetic molecules will provide robust materials having bioactivities governed by cell surface molecules. In this review, recent studies on surface engineering of living mammalian cells are summarized. The engineering processes are categorized into three classes: chemical, physical and biological. According to the cell surface engineering, cell functions such as adhesion, migration, tissue homing, and cell-cell interactions can be controlled. They may be useful for cell-mediated therapies. Furthermore, the novel strategy for making polymeric biomaterials bearing glycoproteins, which may work as targeting ligands for inflammation tissue is also introduced. Keywords: Surface Modification / Cell-Mediated Therapy / Glycoprotein / Drug Delivery System |
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